Typically, a double clutch transmission implies a transmission having two clutch devices. A double clutch transmission generally receives a torque input from an engine selectively at its two input shafts using two clutches. The double clutch transmission then changes the torque and speed using gears on the two input shafts and outputs torque and speed accordingly. Such a double clutch transmission has been devised basically to compactly provide multi-speed transmission of higher than five-speeds. The two clutches and synchronizing devices included in a double clutch transmission may be controlled by a controller, and accordingly, such a double clutch transmission may also realize an automated shift gear (ASG) that eliminates the necessity of manual shifting by a driver.
A typical clutch included in a double clutch transmission may be categorized as both dry- and wet-types based on its operational scheme. A dry-type clutch utilizes the same principle as a clutch device conventionally disposed between an engine and a manual transmission. A wet-type clutch utilizes the same principle as a clutch device inside a typical automatic transmission.
A wet-type clutch generally has a higher torque capacity than a dry-type clutch. Therefore, for an engine of high output power, the wet-type clutch is appropriate. For stable transmission of a high output torque of a high powered engine, widths of gears in the transmission should also be great. Therefore, a drawback of a double clutch transmission designed for a high torque engine is that the double clutch transmissions often become very lengthy.
[The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention, and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art.]